Burn injuries represent a major public health problem, requiring medical attention for more than one million Americans annually. Despite therapeutic advances, non-healing burn wounds and excessive scarring still result in significant long-term physical and psychosocial morbidity. In this P20 Exploratory Center Grant application, we propose to perform clinical and pre-clinical research to study the role of endothelial progenitor cells (EPCs) in promoting burn wound healing. EPCs have been shown to contribute to vascularization and tissue repair in animal models of ischemia. Mobilization of EPCs into the peripheral blood has been demonstrated in burn wound patients. The proposed research will utilize: clinical resources of the Johns Hopkins Regional Burn Center, where hundreds of adults are treated each year;a mouse model of burn wound healing established by participating clinician-scientists;and expertise concerning the cellular and molecular mechanisms of angiogenesis induced by hypoxia/ischemia. The overall goal of the proposed research is to test the hypothesis that the mobilization of bone marrow-derived EPCs and their recruitment to burn wounds is a major determinant of the extent and quality of healing and that strategies designed to promote EPC mobilization and recruitment will promote burn wound healing. The proposed research is thus inherently translational. At the molecular level of analysis, we will focus on the role of hypoxia-inducible factor 1 (HIF-1), a transcription factor that functions as a master regulator of ischemiainduced angiogenesis, although its role in burn wound healing has not been investigated to date. Our highrisk strategy will involve attempting to mobilize and recruit EPCs to burn wounds by increasing the expression of HIF-1 and/or levels of cytokines encoded by HIF-1-regulated genes. To form the nucleus of the Johns Hopkins Center for Innovative Wound Healing Research, we have assembled an interactive multidisciplinary team with expertise in molecular and cellular biology, medical genetics, animal models of wound healing, and clinical burn wound care and research. This team will work together to perform a single project encompassing the innovative studies described above, which will provide the scientific foundation for clinical trials to be proposed in a subsequent P50 application, which will be submitted during year 3 of P20 funding and will lead to novel treatments to promote wound healing and prevent excessive scarring.